Insolation: Life's Not Fair

Insolation is a word that looks wrong, but look again. Not "insulation," but something entirely different. Insolation is the measure of how much solar radiation falls on a horizontal surface in a location per hour during daylight.

What heats up my sunroom is solar energy filtering through atmosphere, clouds, rain, trees and leaves, bug poop, dirt and glass before entering my house and being absorbed as heat by floor and furniture. In New England we get a certain amount, on the average, quantified in kilowatt hours (like the power through your electric meter) per square meter ( I like feet, but engineers can be so, so... metric) per hour. Insolation varies from sunrise to sunset, changes as clouds and fog drift over the land, and varies seasonally as the sun rises higher and sometimes not as high in the sky.

What frosts my root beer is that we get around 3 of these units of insolation, on average. And Taos, New Mexico gets...... 7. See the map, or use the link to get a larger image. Yes, there's a slight difference of latitude, yes the climate is drier, but it's not fair. If New England got all the solar energy that New Mexico gets, we could...... be New Mexico, I suppose.

The reason our solar panels are only a fraction as productive as those installed in the Sun Belt, the reason our sunrooms don't heat our houses completely, the reason our porches and decks are only fun to use for four months a year or so, is a blend of factors including temperature, cloud density, latitude, rainfall and forestation (frequency, height and shade potential of trees).

And I don't like it. But I'm not moving. So beware when solar panel salespersons, greenhouse companies, window and door manufacturers promise you amazing results from solar heating. We get some, yes, but not as much as Taos, or Miami, or Atlanta. And in March, when I'm tired of being cold, I think we don't get our share.